RC7620-1 problem registering to the network

IoT Modules RC76
1

We are having issues with RC7620-1 modem connection to the network in specific places like Australia while no issue in other places.
The modem starts OK and we get the CREG: 0 and CREG: 2 but nothing else after that. It just hangs there until our 5 minute timeout. I have tried to set RAT switching to auto and using *PSRDBS command to set supported frequency bands.

ATE1
OK
ATZ
OK
AT+KSLEEP=2
OK
AT&D0
OK
AT&K3
OK
AT!MUSLEN=1
OK
AT+CPMS="ME","ME","ME"
+CPMS: 0,255,0,255,0,255

OK
AT+CNMI=2,1,0,0,0
OK
AT+CMGF=1
OK
AT+CMEE=1
OK
AT+KSREP=1
OK
AT+KSRAT=0
OK
AT+CREG=1
OK
AT+CGREG=1
OK
AT+COPS=3,2
OK
AT+COPS?
+COPS: 0

OK
AT&W
OK

at*psrdbs=1,524288
OK
at&w
OK
at+cfun=1,1
OK

+CREG: 0

+CGREG: 0

+CEREG: 0

+CREG: 2

+CGREG: 2

+CEREG: 2

+WDSI: 0

+SIM: 1

+KSUP: 0

at+CEREG?
+CEREG: 2,2

OK
at*psrdbs?
*PSRDBS: 524288

OK
at+creg?
+CREG: 1,2

OK
at+cgreg?
+CGREG: 1,2

OK
at+ksrat=?
+KSRAT: (0,1,2,4,5,7,9)

OK

at+ksrat?
+KSRAT: 0

OK

Here are the modem details:
Manufacturer of modem: Sierra Wireless, Incorporated
Type of modem: RC7620-1
Modem firmware version: SWI9X07H_00.08.07.00 0ce4c1 jenkins 2021/03/17 02:18:20
Modem Baudrate: 115200

I tried switching to the supported frequency bands B1 and B3 in Australia using the *PSRDBS command

2

Did you set APN correctly?
What is the return of at!impref?
What is at!gstatus?
Did you find problem on Release 9?

3

APN? is that necessary for network registration? I set APN before trying to connect to the server, but before then I check if the modem is registered to the network using AT+CREG? command with a response of either 1 or 5.

I have not tried any other Firmware, do you mean I should upgrade the modem Firmware to release 9?

4

I think APN is needed for LTE network.

yes, you can try Release 9

BTW, you need to isolate if this is SIM card issue.

5

Yes, setting APN before waiting for connection works. Thanks for that information.

6

I am having the same issue.

Can you confirm that this is resolved by issuing “AT+KCNXCFG=…” (setting the APN) before waiting for network registration “AT+CEREG”?

The order of commands we are using to initiate a connection frequently fails:
AT+KSREP? (check SIM card is active)
AT+CEREG? (wait for network, we frequently get undocumented result code 4 here, but proceed when status 1 or 5 is returned, this will often report 2 ‘searching for an operator’ in known good coverage areas)
AT+KCNXCFG=… (set the APN, configure the connection)
AT+KTCPCFG=… (configure the TCP socket)
AT+KTCPCNX=… (this is where the weirdness starts, but that is for another time)

Can you confirm that issuing KCNXCFG before testing the network with CEREG is the recommended order?

7

the APN for network registration should be set by AT+CGDCONT.

8

Can the AT+KCNXCFG command be omitted if the PDP context is configured with AT+CGDCONT?

9

If just for network registration in AT!GSTATUS, i remember there is no need to set +KCNXCFG

But seems you need to set up +KTCP command, so you also need to set APN in +KCNXCFG